/Engine/Plugins/Animation/ControlRig/Source/ControlRig/Public/Units/RigUnit.h
Base class for all rig units that can change data
[USTRUCT](Programming/UnrealArchitecture/Reference/Structs)([BlueprintType](Programming/UnrealArchitecture/Reference/Structs/Specifiers/BlueprintType), Meta=(Abstract)) struct FRigUnitMutable : public [FRigUnit](API\Plugins\ControlRig\Units\FRigUnit)
FControlRigExec...
ExecuteContext
This property is used to chain multiple mutable units together